This invention relates to the detection and indication of hazardous conditions, particularly those associated with potential or actual combustion malfunctions involving the release of toxic agents, such as escaping fuel gasses and carbon monoxide, as well as excessive smoke and heat.
During and prior to combustion there can be an inadvertent and objectionable escape of fuel gases. If the combustion is incomplete, carbon monoxide can be generated, along with carbon particles that form a sooty smoke. In some cases the combustion can generate excessive heat.
Numerous devices are available for the detection of such hazards. In general the devices for gas detection are highly specialized, and often excessively complex and expensive.
One example of a specialized device for the detection of hazardous gasses is the "Battery Powered Gas Level Indicator" of U.S. Pat. No. 4,250,737 issued Feb. 17, 1981 to Timothy J. Biglin. In the '737 patent, a gas level indicator incorporates two sensing elements and a comparator for signalling a dangerous increase in gas level associated with on-site gas leaks. This device not only is limited in its capability, but also unduly complex.
Another specialized device is the "Gas Sensing Instrument" of U.S. Pat. No. 4,847,783 issued Jul. 11, 1989 to Richard Grace, et al. In the '783 patent there is programmable control over the operating temperatures of an array of gas sensors. This arrangement quantifies the concentrations of gasses in an oxygen-containing atmosphere using a computer in a complex equipment arrangement. This device also is limited in its capability.
While the quantification of gas concentration can meet specialized needs, there is a general need for merely indicating the presence of an undesirable concentration. Consequently the specialized and limited capability of this instrument is not of general utility.
A further specialized device is the "Semiconductor Gas Sensor Having Linearized Indications" of U.S. Pat. No. 5,034,725 issued Jul. 23, 1991 to Thomas C. Sorensen. In the '725 patent exhaust gases are measured and indicated by a sensor for which conductivity varies in accordance with variations in the concentration of the ambient exhaust. Like the '783 patent mentioned above, the device of patent '725 is complex and of limited applicability.
Accordingly, it is an object of the invention to facilitate the detection and indication of hazard conditions, particularly those relating to the objectionable presence of gasses and heat, particularly those conditions associated with exhausts and combustion. A related object of the invention is to provide a facility for gas, heat and smoke detection in a portable unit that is suitable for domestic as well as commercial use.
A further object of the invention is to provide a generalized detection and indication device for hazardous gasses, smoke and heat.
A further object of the invention is to achieve hazard indication in a reliable and economic way, so that the detection capability associated with complex and expensive instrumentalities can be made available to ordinary users and thus provide for enhance community security.